Ready for the summer before her senior year to be the best one yet, Penny Harris finds herself without a boyfriend and a best friend after she kisses Kai Tanaka, her best friend's boyfriend, at the big first-day-of-summer party. When her ex-boyfriend Jordan starts hanging out with her ex-best friend Olivia more and more, Penny and Kai come up with a plan to win back their respective partners by faking a relationship. But as the summer progresses, Penny starts to wonder if her feelings for Kai are really just for show.